The repair of damaged conduits using a resin-impregnated repair material is known in the art. For example, U.S. Pat. Nos. 4,361,451, 5,049,003 and 5,203,377 each describe a system for repairing ruptures or cracks in a conduit such as a sewer conduit. Each of these systems involves a resin-impregnated liner or sleeve which is wrapped around an inflatable core member. The core member and liner are introduced into the conduit and are positioned in proximity to the rupture or crack. The core member is then inflated so as to exert pressure on the liner causing the resin-impregnated liner to become securely engaged with the inner wall of the conduit. The resin is permitted to cure so as to engage the liner to the conduit, and afterwards the core member is deflated and removed from the conduit leaving the liner in place.
There are, however, several drawbacks associated with conventional systems using an inflatable core member. For example, the core member and liner must be inserted into the conduit through an opening and pulled accurately into position with respect to the rupture or crack. During this insertion process, the core member and liner are oftentimes twisted, bent, and dragged against the walls of the opening to the conduit and the conduit itself. Because the repair liner in the past has simply been wrapped around the core member, the abrasive action during the installation process tended to cause the repair liner to shift in position relative to the core member. As a result, it has been difficult to position properly the repair liner in the conduit in relation to the crack or rupture.
Still another drawback associated with conventional systems has been damage caused to the repair liner during insertion of the core member and liner into the conduit. The leading edge of the repair liner as it is inserted into the conduit tends to be raised relative to the core member due to its being wrapped around the outer circumference of the core member. As a result, the leading edge tends to get caught or snagged due to discontinuities in the opening to the conduit and/or in the conduit itself. This causes pulling and possible tearing of the repair liner. Furthermore, it can result in a shifting of the repair liner on the core member.
Yet another drawback in the past has been the lack of a suitable repair liner material that provides both strength and durability. In particular, conventional repair liner materials failed to provide both a lining in the conduit which had the strength of fiberglass or the like yet still tended to resist corrosion caused by the corrosive compositions oftentimes found in sewers.
Moreover, conventional repair systems using an inflatable core member often necessitated a blocking of the conduit for an extended period of time. As a result, bypassing of the portion of conduit being repaired was required. This has been difficult to accomplish, especially with sewers. Other systems, such as the one described in the above-mentioned U.S. Pat. No. 5,203,377, include a coaxial duct in the core member which permits flow through the core member during the repair process.
Still another drawback associated with conventional systems has been the use of a release agent to facilitate removal of the core member from the repair liner following the curing of the resin. In the past, the release agent has been applied to the outer surface of the core member prior to the resin-impregnated repair liner being wrapped around the core member. After the repair liner is installed in the conduit and the core member retrieved, it has been necessary to clean the release agent and any residual resin from the surface of the core member. This requires substantial time and effort thereby undesirably increasing the overall cost of the repair process.
Some systems, such as the system described in U.S. Pat. No. 5,203,377, rely on the eversion of an outer sleeve of the core member to separate the core member from the repair liner. As the core member is removed from the conduit, the outer sleeve is progressively everted and peeled away from the repair liner. A particular drawback associated with this type of system has been that if the resin has not completely cured prior to removal of the core member, the eversion of the outer sleeve tends to peel portions of the repair liner off the wall of the conduit.
Yet another drawback associated with conventional systems relates to the occurrence of uneven curing of the resin in the repair liner. Typically, water under pressure is introduced into the core member in order to inflate the core member. The temperature of the water is adjusted to heat the core member in order to facilitate curing of the resin. Unfortunately, the temperature across the length of the core member has tended to vary significantly. This has resulted in uneven curing of the resin.
In view of the aforementioned shortcomings associated with conventional repair systems, there is a strong need in the art for a repair system in which the repair liner is fixed in position while the core member is inserted into the conduit. There is also a strong need for a repair system in which at least the leading edge of the repair liner is protected from damage during the installation procedure. Furthermore, there is a strong need in the art for a repair liner material which is both strong and durable. In addition, there is a strong need for a repair system which includes a flow through apparatus for permitting flow through during the installation procedure.
It will also be appreciated that there is a strong need in the art for a repair system which does not require clean up of a release agent and/or residual resin from the core member following installation. Moreover, there is a strong need in the art for a repair system which includes a core member having circulation means for forming a substantially constant temperature regime over the entire length of the core member.